Xerographing fixing method and apparatus



g- 23, W65 w. G. VAN DORN 3,268,3

XEROGRAPHING FIXING METHOD AND APPARATUS Original Filed June 29, 19 61 3 Sheets -Sheet 1 INVENTOR. WARREN c. VAN DORN FIIGZ I mp M/ ATTORNEY IN V EN TOR. WARREN G. VAN DQRN ATTORNEY Aug. 23, 1966 w. G. VAN BORN xmoempmue FIXING METHOD AND APPARATUS 3 Sheets-Sheet 2 Original F iled June 29, 1961 w? fii ,lmf Q Q M R mm m xv Q wk wm a i W v mm .w IZ.ZEE. E; .Z, 2! k. ww I I l. 1 .w. 6 mm Au 23, mm we. VAN DORN 3,268,351

XEROGRAPHING FIXING METHOD AND APPARATUS Original Filed June 29, 1961 5 Sheets-Sheet 3 FIG. 5 .7 F/GJ6 120 v ao- INVENTOR. 8 WARREN c. VAN DORN ATTORNEY United States. Patent r 3,268,351 XERGGRAPHING FIXING METHOD AND APPARATUS Warren G. Van Dorn, Columbus, Ohio, assignor, by

mesne assignments, to Xerox Corporation, Rochester, N.Y., a corporation of New York 4 I Continuation of application Ser. No. 120,755, June 29, 1961. This application Feb. 17, 1964, Ser. No. 346,585

: Y 5 Claims. (Cl. 117-21) This application is a continuation of copending application, Serial No. 120,755, filed June 29, 1961, and now abandoned.

' This invention relates toimprovements in heat fusing devicesand, particularly, to an improved apparatus for fixing xerographic powder images. More specifically, the invention relates to animproved heated-roll fusing device. Although the invention is considered tohave general application, it is particularly useful in the field of xerography and has an important application in the fusing of resinous powder images produced by electrophotography or xerography onto sheets of paper and the like to which the powder images have been transferred after they have been formed by deposition of powder on an electrostatic latent image. Therefore, for convenience of illustration, the invention is described with reference to its use as' a heat fuser for xerographi powder images. However, it is to be understood that it may be employed with equal facility in other fields.

v In theprocess of xerography, for example, as disclosed in Carlson Patent 2,297,691, issued October 6, 1942, a xerographic plate, comprising a layer of photoconductive insulating material on a conductive backing, is given a uniform electric charge over its surface and is then exposed to the subject matterto be reproduced, usually by conventional projection techniques. This exposure discharges the plate areas in accordance with the radiation intensity that reaches them, and thereby creates an electrostatic latent image on or in the photoconductive layer. Development. of the latent image is effected with an electrostatically charged, finely divided developing material or tonerwhich is brought into surface contact with the photoconductive layer and is held thereon electrostatically in a pattern corresponding to the electrostatic latent image. Thereafter, the developed xerographic powder image is usually transferred to a support surface, such as paper, to which it may be fixed by any suitable means.

One of the methods in common use for developingthe elastrostatic latent image is described in Walkup Patent 2,618,551, and is known as cascade development, and is in general use for line copy development. In this technique, the powder or toner is mixed with a granular car rier material, and this two-component developer is poured or cascaded over the plate surface. The function of the carrier material is to improve the flow characteristics of the powder and to produce, on the powder, by triboelectrification, the proper electrical charge so that the powder will be attracted to the image. More exactly, the function of the carrier material is to provide the mechanical control to the powder, or to carry the powder to an image surface and, simultaneously, to provide homogeneity of polarity.

, In the Carlson patent it is noted that a variety of types of finely divided electroscopic powders may be employed for developing electrostatic latent images. However, as the art of xerography has progressed, it has been found preferable to develop line copy images with a powder or toner formed of any of a variety of pigmented thermo plastic resins that have been specifically developed for the purpose. A number of such developing materials are available commercially, and these developing materials are specifically compounded for producing dense images of high resolution and to have characteristics to permit convenient storage and handling. Such developing materials are compounded to permit them to be fixed to the surface of a transfer material either by heat fixing or vapor fixing techniques, in accordance with the particular application in which they are employed, that is, the individual particles of resin (toner) soften and coalesce when heated or plasticized by solvent, so that they become sticky or tackified and readily adhere to the surface of the transfer material. a

The term tackified and the several variant forms thereof used throughout this specification are employed to define the condition of the powder particles of the Xerographic powder image when heated or plasticized by a solvent in a manner such that the individual particles soften and coalesce and in which state they become sticky and readily adhere to other surfaces.- Although thiscondition necessarily requires a flowing together of the particles to effect a thorough fusion thereof, it is to be understood that the extent of such flowing is not sufiicient to'extend beyond the boundary of the pattern in which the particles are formed. p 7

One of the important applications of the process of xerography comprises its use in automatic copying machines for general ofiice use wherein the powder images formed on a xerographic plate are transferred to paper and then fixed thereon by heat fusing. In order to fuse resinous images formed of the powdered resins now commonly used, it is necessary to heat the powder and the paper to which it is to be fused to a relatively high temperature, such as approximately 325 F. It is undesirable, however, to raise the temperature of the paper substantially higher than 375 F. because of the tendency of paper to discolor at such elevated temperatures.

It has long been recognized that one of the fastest and most positive methods of applying heat for fusing the powder image to paper is to bring the powder image into direct contact with a hot surface,- such as a heated flat plate.-

But, as the powder image is tackified by heat, part of the image carried by the support material will stick to the surface of the heated plate, so that as the next sheet is placed on the heated plate the tackified image partially removed from the first sheet will partly transfer to the next sheet and at the same time part of the tackified image from said next sheet would adhere to the heated plate.- This process is commonly referred to in the printing art,- as set off or offset, the latter term being preferred.

The offset of toner onto the heated contacting surface has heretofore led to the rejection of contact fusers in favor of other heat fixing devices, primarily coiled radiant element heaters with reflectors. These radiant element heaters with refleotoms have the disadvantage of dissipating a large quantity of heat into the machine enclosure in which they are used, heat transfer to the powder image is inefficient, and they present a safety hazard because of the exposed radiant element.

It is, therefore, the principal object of this invention to improve the construction of a direct contact fusing device for toner images which will rapidly fuse toner images while preventing toner offset.

Another object of this invention is to improve the con struction of a direct contact fusing device to attain efficient heat transfer to the toner image to be fused.

It is still another object of the invention to improve the construction of a heat fixing device to have low stand-by power requirement.

A still further object of this invention is to improve the method for fusing toner images on support material.

Another object of this invention is to improve the method of fusing toner images while preventing toner offset.

These and other objects of the invention are attained by means of a dire-ct cont-act fusing device in which the toner image is fused by forwarding the sheet or web of paper bearing the toner image between two heated rolls, the roll contacting the image being provided with a thin coating of a Du Pont Corporation product composed of t-etnalfluoroethylene [resin sold under the trademark Teflon, and a silicone oil film to prevent toner offset. Both the Teflon and silicone oil have such physical characteristics that they are substantially adhesive to dry or tackified xerographic developing materials. Abhesive is a relatively new term that was coined by Dow Corning Corporation, primarily in connection with their silicones to define a surface that has release characteristics such that it is highly repellent to sticky or tacky substances. The word is adopted in this sense herein and is so used throughout the disclosure.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings wherein:

FIG. 1 illustrates schematically a preferred embodiment of an electrophot-ographic apparatus adapted for automatic operation, and incorporating a heat fuser constructed in accordance with the invention;

FIG. 2 is a right-hand end view of the heat fuser of the invention;

FIG. 3 is a sectional view of the heat fuser taken along line 33 of FIG. 2; I

FIG. 4 is a sectional view taken along line 44 of FIG. 2;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 4;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 4;

FIG. 7 is a sectional view taken along line 77 of FIG. 4; and,

FIG. 8 is a schematic electrical wiring diagram of the heater elements of the heat fuser.

Although it forms no part of the subject invention, there is shown schematically in FIG. 1 a continuous Xerographic apparatus for the purpose of illustrating a suitable environment for a heat fuser having mounted therein heating elements of the subject invention.

As shown in FIG. 1, the xerographic apparatus comprises a xerographic plate including a photoconduct ve layer or light-receiving surface on a conductive backing and formed in the shape of a drum, gene-rally designated by numeral 10, which is mounted on a shaft 11 journaled in a frame (not shown) to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of xerographic processing stations. Dru-m is rotated at a constant rate through the drive action of synchronous motor 12.

For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the drum surface may be described functionally, as

follows:

A charging station, at which a uniform electrostatic charge is deposited on the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof and thereby form a latent electrostatic image of the copy to be reproduced;

A developing station, at which a xerographic developing material, including toner particles having an electrostatic charge opposite to that of the electrostatic latent image, is cascaded over the drum surface, whereby the toner particles adhere to the electrostatic latent image to form a xerographic powder image in the configuration of the copy to be reproduced;

A transfer station, at which the xerographic powder image is transferred from the drum surface to a transfer material or support surface; and

A drum cleaning and discharge station, at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge thereon.

In general, the charging apparatus 13, which may be of the type disclosed in Walkup Patent 2,777,957, includes a corona discharge array of one or more corona discharge electrodes that extend transversely across the drum surface and are energized from a high potential source and are substantially enclosed within a shielding member.

Next subsequent thereto in the path of motion of the xerographic drum is an exposure station. This exposure station may be one of a number of types of mechanisms or members, such as desirably an optical projection system 14, or the like, designed to project a line copy image onto the photoconductive surface of the XCIO'. graphic drum from an original, as is well known in the art.

Adjacent to the exposure station is a developing station in which there is positioned a developer housing 15 including a lower or sump portion for accumulating developing material 16. A bucket type conveyor 17 having a suitable driving means, such as motor 18, is used to carry the developing material to the upper part of the developer housing where it is cascaded down over a hopper chute 21 onto the xerographic drum.

As the developing material is cascaded over the xerographic drum, toner particles are pulled away from the carrier component of the developing material and deposited on the drum to form powder images, while the partially denuded carrier particles pass off the drum into the developer housing sump. As toner powder images are formed, additional toner particles must be supplied to the developing material in proportion to the amount of toner deposited on the drum. For this purpose, there is provided a container 22 for toner 23 to be added to the developing material as needed, the toner being added at a rate determined by control gate 24.

After development, the image thus formed is transferred to support surface web 25, which may be paper or any other suitable material. Web 25 is continuously transported from supply spool 26 to take-up spool 27 by a suitable paper handling apparatus which may be of the type disclosed in Crnmr-ine et al. Patent 2,781,705. The paper handling mechanism includes a synchronous motor 31 driving take-up spool 27, while guide rolls 33 serve to direct the web 25 into contact against a powder image on the surface of drum 10. Electrostatic transfer unit 35, which may be of a type similar to unit 13, generates an electrostatic charge to electrostatically attract the powder image from the surface of drum 10 to web 25.

Thereafter, image-bearing web 25 is transported through heat fuser 40, of the type disclosed in detail hereinafter, whereby the developed and transferred xero graphic powder image on the web 25 is permanently fixed thereto, the web thereafter being guided by idler rollers 34 to take-up spool 27.

The next and final station in the device is a drum cleaning and discharge station where any powder remaining on the xerographic drum after transfer is removed by rotating brushes and the xerographic drum is flooded with light to cause dissipation of any residual electrical charge remaining on the xerographic drum. The residual powder image on the surface of drum after transfer is removed by brushes 36 driven by motor 37 after which any residual electrostatic charge remaining on the drum is dissipated by illumination from lamp 38.

Referring now to FIGS. 1 through 7, inclusive, there is shown a' preferred embodiment of a direct contact fusing device 40 constructed in accordance with the invention.

In the embodiment shown, the direct contact fusing device includes a frame, for supporting the remaining components of the fuser, formed by flanged, cup-shaped, left-hand end plate 41 and right-hand end plate 42 connected together and maintained rigidly in spaced-parallel relation to each other by tie plates 43 and 44 secured thereto as by welding. The tie plates 43 and 44 have polished surfaces which act as reflectors to reflect heat back toward the heating elements of the fuser and the paper or other transfer material forwarded therebetween, as described in detail hereinafter.

Direct contact fusing is achieved by forwarding the web 25 hearing the toner image to be fused between a pair of heated contact fusing rolls, generally designated 45 and 55, journaled for rotation between the end plates 41 and 42.

Roll 45 includes a cylinder 46 closed at one end by bushing 47 and at its other end by bushing 48, and is driven by gear 51 secured on the outboard side of bushi'ng'48as' by pins 52 extending through the gear and the bushing. The roll 45 is journaled for rotation by means of sleeve bearings 58 positioned on flanged bearing supports 59 inserted through suitable apertures formed in end plates 41 and 42. a

Roll 55, similar in structure to roll 45, includes cylinder 56 covered to prevent toner offset with a suitable material 57, such as a coating of a product of tetrafluoroethylene resin sold under the trademark of Teflon *by the Du Pont Corporation. Teflon is a chemically inert, non-porous and non-absorbent, relatively hard and generally form-retaining, wax-like synthetic resin which is slightly elastic under low stress and which is capable of cold-flowing under greater stress, and which is capable of sliding over a surface in the manner of self-lubricating relationship therewith. The cylinder 56 is closed at opposite ends by bushings 47 and 48, the bushing 48 also having secured thereon, by pins 52, a gear 53. Flanged bearing supports 61 carry sleeve bearings 58 to rotatably support the roll 55. The flanged bearing supports 61 are mounted in plates 62 secured in adjustable position on the end plates 41 and 42 by means of pins 63 which are secured to the end plates 41 and 42 and project through elongated slots provided in the plates 62.

With this mounting arrangement, roll 55 will remain in contact with roll 45 or a web of support material sandwiched therebetween merely by the weight of the roll itself, it being realized that the variation in the distance between the centers of rolls 45 and 55, as roll 55 is moved out of contact with roll 45 to accept a web of sup port material therebetween, is so limited that the gears 51 and 53 will remain in engagement with each other, whereby the roll 55 is driven through these gears at a speed equal to the rotational speed of roll 45.

To supply heat necessary to fuse the toner images on the support material, there is provided in each of the rolls 45 and 55 a suitable resistance heating element. In the embodiment shown, the heating elements are formed of a suitable resistance wire in the form of a coil to form resistance heating elements R-1 and R2 for rolls 45 and 55, respectively. The coiled resistance elements are the shoe from marking the portion of this roll in con- 7 each supported on a core 66 made of a suitable insulating material, for example, a ceramic material such as porcelain. The cores 66=are supported within their respective roll and out of contact therewith by means of rods 67 which extend through suitable apertures in bushings 47 and 48 and through the flanged bearing supports 59 and 61. Longitudinal alignment of the cores within the rolls is maintained by means of collars 68 encircling the ends of the rods and abutting the flanged ends of the bearing supports.

As shown schematically in FIG. 8, the resistance elements R-1 and R-2 are connected by suitable conductors to a source of 'power, such as a commercial 120 voltage, 60 cycle alternate current outlet. A thermostat THS is mounted in a shoe 71 secured by screws 72 extending through the up-turned portions of tie plate 44, whereby the shoe is maintained in rubbing contact with roll 45, the shoe being located at one end of the roll to keep tact with the underside of the web 25.

To further prevent offset of toner onto the heated contact surface of roll 55, which in the embodiment shown will contact toner on the upper surface of web 25, a roll type applicator is used to supply a thin film of offset preventing liquid, such as silicone oil, to the Teflon (polytetrafiuoroethylene polymer) coating on roll 55.

Although various means may be used to apply the,

silicone oil to roll 55 in the preferred embodiment of the invention, there is used an applicator roll 75 suitably journaled on axle 76 which extends through slots formed at an angle to the horizontal plane, in end plates 41 and 42 and in plates 62, whereby the roll is adapted to rest in peripheral contact with the surface of roll 55. The applicator roll is maintained in position by means of adjusting screws 65 threaded in turned out portions 64 of plates 62 whereby the ends of the adjusting screws abut against the axle 76. The applicator roll 75 is driven in timed relation to roll 55 by gear 77 secured to one end of the axle 76 of the applicator roll, the gear 77 engaging the gear 53 on roll 55.

When the rolls are rotated, the applicator roll 75 picks 7 up oil from a saturated felt pad 78 positioned in the open oil reservoir 81 secured between end plates 41 and 42. Oil is fed to the reservoir through a suitable commercial constant-level device, not shown, and the oil entrance elbow 82 connected to the reservoir, whereby oil saturation of the felt pad 78 is maintained. Oil picked up by the applicator roll from the felt pad is then thinned to the desired thickness by the doctor blade 83 before it is deposited on roll 55. The doctor blade 83 is pivotably supported adjacent to applicator roll by means of shoulder screws 84 whereby the doctor blade will rest against the applicator roll.

The rolls 45 and 55 are driven in synchronization to the speed of movement of web 25 by means of drive shaft 91 adapted to be connected to a separate drive mechanism or to the paper drive mechanism, such as motor 31, of the machine whereby these rolls are maintained in rolling contact with the web, since sliding contact between the rolls and web would cause smearing of the toner image. Drive shaft 91 journaled in suitable bearing supported on end plate 42 has gear 92 fixed thereon which drives gear 51 of roll 45 through intermediate gear 93 mounted on stub shaft 94 journaled in bearing 86 secured to end plate 42.

A suitable paper guide 95 is secured to end plates 41 and 42 and extends therebetween to guide the web 25 between the rollers 45 and 55.

While the present invention as to its objects and advantages, as described herein, has been carried out in specific embodiments thereof, it is not desired to be limited thereby, but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. A fusing device for use in a xerographic reproducing apparatus for fixing a resin base powder image onto a support surface to which the powder image is loosely adhering, said fusing device including a frame,

a pair of rolls, including an upper roll and a lower roll journaled in parallel relation to each other in said frame,

said upper roll having a coating of tetrafluoroethylene polymer on its peripheral surface,

means connected to said frame to apply silicone oil to the tetrafluoroethylene polymer coating of said upper roll,

means to heat said tetrafluoroethylene polymer coated upper roll,

means to move the support surface with the powder image thereon through the rolls with the powder image in contact with the tetrafluor oethylene polymer coated roll, and

drive means connected to said upper roll and said lower roll to drive said rolls, said upper roll being heated sufiiciently and said upper roll cont-acting the surface of the support surface carrying the powder image with just enough pressure whereby said powder image is fused to said support surface without degradation of the powder image on the support surface as the support surface is advanced between said rolls.

2. A fusing device for use in a xerographic reproducing apparatus for fixing a resin base powder image onto a support surface to which the powder image is loosely adhering, said fusing device including a support means,

a pair of rolls, including an upper roll and a lower roll journaled in parallel relation to each other in said support means,

said support means including means to force a support surface into intimate contact with said upper roll with the surface of the support surface carrying the powder image in contact with said upper roll,

said upper roll having a relatively hard coating of an offset preventing material on its peripheral surface,

means connected to said frame to apply an offset preventing liquid to the relatively hard coating of offset preventing material on said upper roll,

means to heat said upper roll to a temperature sufficient to tackify the resin base powder image,

means to move the support surface with the powder image thereon through the rolls with the powder image in contact with the upper roll, and,

drive means connected to said upper roll and said lower roll to drive said rolls, said upper roll being heated sufficiently and said upper roll contacting the surface of the support surface carrying the powder image with just enough pressure whereby said powder image is fused to said support surface without degradation of the powder image on the support surface as the support surface is advanced between said rolls,

wherein the offset preventing material on the peripheral surface of the upper roll is tetrafluoroethylene polymer and the offset preventing liquid applied to the upper roll is silicone oil.

3. A fusing device for use in a xerographic reproducing apparatus for fixing a resin base powder image onto a support surface to which the powder image is loosely adhering, said fusing device including a support means,

an upper roll having a relatively hard coating of an offset preventing material on its peripheral surface and a lower roll journaled in parallel relation to each other in said support means with the peripheral surfaces of said upper roll and of the lower roll movable with respect to each other from a first position in which the peripheral surfaces of the upper 8 roll and lower roll are in contact with each other to a second position in which the upper roll and lower roll-are adapted to cooperate with each other to advance a support surface therebetween with the surface of the support surface carrying the powder image in contact with the upper roll,

applicator means connected to said support means to apply a coating of an offset preventing liquid to the peripheral surface of said upper roll,

means to move the support surface with the powder image thereon through the rolls with the powder image in contact with the upper roll,

heating means in thermal contact with said upper roll to heat said upper roll to a temperature sufficient to tackify the resin base powder image, and

drive means connected to said upper roll and said lower roll to drive said upper roll and said lower roll to advance a support surface therebetween into and out of contact with said upper roll,

' said upper roll being heated sufficiently and contacting the surface of the support surface carrying the powder image with enough pressure whereby said powder image is fused to said support surface without degradation of the powder image on the support surface or the support surface itself as the support surface is advancedbetween said rolls,

wherein the offset preventing material is tetrafluoroethylene polymer and the offset preventing liquid is silicone oil. 4. The method of fixing a resin base powder image onto a support material to which the powder image is loosely adhering, comprising the steps of heating an offset preventing surface comprising tetrafluoroethylene polymer to a temperature sufficient to tackify the resin of the resin base powder image,

applying a coating of an offset preventing liquid comprising a silicone oil to the offset preventing surface,

advancing the support material into contact with the offset preventing surface in a manner to place the surface of the support material bearing the powder image in contact with the offset preventing surface,

forcing the support material and the offset preventing surface into intimate surface contact with sufficient pressure to insure good thermal contact between these surfaces without causing degradation of the powder image on the support material and thereby heating the powder image to a temperature sufiicient to tackify the powder image,

and removing the support material from contact with the offset preventing surface to expose the tackified powder image to ambient air, thereby to permit the tackified powder image to harden and leave a fixed resin base image on the support material.

5. The method of fixing a resin base powder image 55 onto a support material to which the powder image is loosely adhering, comprising the steps of heating One of a pair of pressure rolls that are rotating in material feeding relation and of which the heated roll is provided with an offset preventing surface comprising tetrafluoroethylene polymer that is heated to a temperature sufficient to tackify the resin of the resin base powder image,

applying a coating of an offset preventing liquid comprising a silicone oil to the surface of the heated roll,

moving the support material to a position to be gripped and advanced by the pressure roll in a manner to place the surface of the support material bearing the 70 powder image in contact with the heated roll,

forcing the support material into intimate contact with the heated roll with sufiicient pressure to insure good thermal contact between the support material surface and the heated roll without causing degradation of the powder image and thereby heating the powder image to a temperature sufficient to tackify the powder image, and removing the support material out of contact with the pressure rolls after the powder image is tackified.

References Cited by the Examiner UNITED STATES PATENTS 9/1912 Crabb 11860 11/ 1937 Bergstein 93-35 11/1953 Zinn 118-202 4/1954 Burke et a1. 118202 7/1958 Gleason 118-637 X 9/1958 Tregay et a1. 11717.5

10 Co., New York, 1958.

OTHER REFERENCES McGregor, R. R.: Silicones and Their Uses, Mc- Graw-I-Iill Book Co., New York, 1954, pp. 65-66, 79. Rudner, M. A.: Fluorocarbons, p. 13, Reinhold Pub.

WILLIAM D. MARTIN, Primary Examiner.

G. L. HUBBARD, Assistant Examiner.

Dedication 3,268,35L-Warren G. van Dam, Columbus, Ohio XEROGRAPHIC FIXING METHOD AND APPARATUS. Patent dated Aug. 23, 1966. Dedication filed Oct. 21, 1982, by the assignee, Xerox Corp.

Hereby dedicates to the Public the entire remaining term of said patent.

[Official Gazette October 18, 1983.] 

4. THE METHOD OF FIXING A RESIN BASE POWDER IMAGE ONTO A SUPPORT MATERIAL TO WHICH THE POWDER IMAGE IS LOOSELY ADHERING, COMPRISING THE STEPS OF HEATING AN OFFSET PREVENTING SURFACE COMPRISING TETRAFLUOROETHYLENE POLYMER TO A TEMPERATURE SUFFICIENT TO TACKIFY THE RESIN OF THE RESIN BASE POWDER IMAGE, APPLYING A COATING OF AN OFFSET PREVENTING LIQUID COMPRISING A SILICONE OIL TO THE OFFSET PREVENTING SURFACE, ADVANCING THE SUPPORT MATERIAL INTO CONTACT WITH THE OFFSET PREVENTING SURFACE IN A MANNER TO PLACE THE SURFACE OF THE SUPPORT MATERIAL BEARING THE POWDER IMAGE IN CONTACT WITH THE OFFSET PREVENTING SURFACE, FORCING THE SUPPORT MATERIAL AND THE OFFSET PREVENTING SURFACE INTO INTIMATE SURFACE CONTACT WITH SUFFICIENT PRESSURE TO INSURE GOOD THERMAL CONTACT BETWEEN THESE SURFACES WITHOUT CAUSING DEGRADATION OF THE POWDER IMAGE ON THE SUPPORT MATERIAL AND THEREBY HEATING THE POWDER IMAGE TO A TEMPERATURE SUFFICIENT TO TACKIFY THE POWDER IMAGE, AND REMOVING THE SUPPORT MATERIAL FROM CONTACT WITH THE OFFSET PREVENTING SURFACE TO EXPOSE THE TACKIFIED 